<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/indexmap-2.7.0/src/lib.rs`."><title>lib.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-42caa33d.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="indexmap" data-themes="" data-resource-suffix="" data-rustdoc-version="1.84.0 (9fc6b4312 2025-01-07)" data-channel="1.84.0" data-search-js="search-92e6798f.js" data-settings-js="settings-0f613d39.js" ><script src="../../static.files/storage-59e33391.js"></script><script defer src="../../static.files/src-script-56102188.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-893ab5e7.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer"></div><main><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">indexmap/</div>lib.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap"><div data-nosnippet><pre class="src-line-numbers">
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<a href="#274" id="274">274</a></pre></div><pre class="rust"><code><span class="comment">// We *mostly* avoid unsafe code, but `Slice` allows it for DST casting.
</span><span class="attr">#![deny(unsafe_code)]
#![warn(rust_2018_idioms)]
#![no_std]

</span><span class="doccomment">//! [`IndexMap`] is a hash table where the iteration order of the key-value
//! pairs is independent of the hash values of the keys.
//!
//! [`IndexSet`] is a corresponding hash set using the same implementation and
//! with similar properties.
//!
//! ### Highlights
//!
//! [`IndexMap`] and [`IndexSet`] are drop-in compatible with the std `HashMap`
//! and `HashSet`, but they also have some features of note:
//!
//! - The ordering semantics (see their documentation for details)
//! - Sorting methods and the [`.pop()`][IndexMap::pop] methods.
//! - The [`Equivalent`] trait, which offers more flexible equality definitions
//!   between borrowed and owned versions of keys.
//! - The [`MutableKeys`][map::MutableKeys] trait, which gives opt-in mutable
//!   access to map keys, and [`MutableValues`][set::MutableValues] for sets.
//!
//! ### Feature Flags
//!
//! To reduce the amount of compiled code in the crate by default, certain
//! features are gated behind [feature flags]. These allow you to opt in to (or
//! out of) functionality. Below is a list of the features available in this
//! crate.
//!
//! * `std`: Enables features which require the Rust standard library. For more
//!   information see the section on [`no_std`].
//! * `rayon`: Enables parallel iteration and other parallel methods.
//! * `serde`: Adds implementations for [`Serialize`] and [`Deserialize`]
//!   to [`IndexMap`] and [`IndexSet`]. Alternative implementations for
//!   (de)serializing [`IndexMap`] as an ordered sequence are available in the
//!   [`map::serde_seq`] module.
//! * `borsh`: Adds implementations for [`BorshSerialize`] and [`BorshDeserialize`]
//!   to [`IndexMap`] and [`IndexSet`].
//! * `arbitrary`: Adds implementations for the [`arbitrary::Arbitrary`] trait
//!   to [`IndexMap`] and [`IndexSet`].
//! * `quickcheck`: Adds implementations for the [`quickcheck::Arbitrary`] trait
//!   to [`IndexMap`] and [`IndexSet`].
//!
//! _Note: only the `std` feature is enabled by default._
//!
//! [feature flags]: https://doc.rust-lang.org/cargo/reference/manifest.html#the-features-section
//! [`no_std`]: #no-standard-library-targets
//! [`Serialize`]: `::serde::Serialize`
//! [`Deserialize`]: `::serde::Deserialize`
//! [`BorshSerialize`]: `::borsh::BorshSerialize`
//! [`BorshDeserialize`]: `::borsh::BorshDeserialize`
//! [`arbitrary::Arbitrary`]: `::arbitrary::Arbitrary`
//! [`quickcheck::Arbitrary`]: `::quickcheck::Arbitrary`
//!
//! ### Alternate Hashers
//!
//! [`IndexMap`] and [`IndexSet`] have a default hasher type
//! [`S = RandomState`][std::collections::hash_map::RandomState],
//! just like the standard `HashMap` and `HashSet`, which is resistant to
//! HashDoS attacks but not the most performant. Type aliases can make it easier
//! to use alternate hashers:
//!
//! ```
//! use fnv::FnvBuildHasher;
//! use fxhash::FxBuildHasher;
//! use indexmap::{IndexMap, IndexSet};
//!
//! type FnvIndexMap&lt;K, V&gt; = IndexMap&lt;K, V, FnvBuildHasher&gt;;
//! type FnvIndexSet&lt;T&gt; = IndexSet&lt;T, FnvBuildHasher&gt;;
//!
//! type FxIndexMap&lt;K, V&gt; = IndexMap&lt;K, V, FxBuildHasher&gt;;
//! type FxIndexSet&lt;T&gt; = IndexSet&lt;T, FxBuildHasher&gt;;
//!
//! let std: IndexSet&lt;i32&gt; = (0..100).collect();
//! let fnv: FnvIndexSet&lt;i32&gt; = (0..100).collect();
//! let fx: FxIndexSet&lt;i32&gt; = (0..100).collect();
//! assert_eq!(std, fnv);
//! assert_eq!(std, fx);
//! ```
//!
//! ### Rust Version
//!
//! This version of indexmap requires Rust 1.63 or later.
//!
//! The indexmap 2.x release series will use a carefully considered version
//! upgrade policy, where in a later 2.x version, we will raise the minimum
//! required Rust version.
//!
//! ## No Standard Library Targets
//!
//! This crate supports being built without `std`, requiring `alloc` instead.
//! This is chosen by disabling the default "std" cargo feature, by adding
//! `default-features = false` to your dependency specification.
//!
//! - Creating maps and sets using [`new`][IndexMap::new] and
//!   [`with_capacity`][IndexMap::with_capacity] is unavailable without `std`.
//!   Use methods [`IndexMap::default`], [`with_hasher`][IndexMap::with_hasher],
//!   [`with_capacity_and_hasher`][IndexMap::with_capacity_and_hasher] instead.
//!   A no-std compatible hasher will be needed as well, for example
//!   from the crate `twox-hash`.
//! - Macros [`indexmap!`] and [`indexset!`] are unavailable without `std`.

</span><span class="attr">#![cfg_attr(docsrs, feature(doc_cfg))]

</span><span class="kw">extern crate </span>alloc;

<span class="attr">#[cfg(feature = <span class="string">"std"</span>)]
#[macro_use]
</span><span class="kw">extern crate </span>std;

<span class="kw">use </span>alloc::vec::{<span class="self">self</span>, Vec};

<span class="kw">mod </span>arbitrary;
<span class="attr">#[macro_use]
</span><span class="kw">mod </span>macros;
<span class="attr">#[cfg(feature = <span class="string">"borsh"</span>)]
</span><span class="kw">mod </span>borsh;
<span class="attr">#[cfg(feature = <span class="string">"serde"</span>)]
</span><span class="kw">mod </span>serde;
<span class="kw">mod </span>util;

<span class="kw">pub mod </span>map;
<span class="kw">pub mod </span>set;

<span class="comment">// Placed after `map` and `set` so new `rayon` methods on the types
// are documented after the "normal" methods.
</span><span class="attr">#[cfg(feature = <span class="string">"rayon"</span>)]
</span><span class="kw">mod </span>rayon;

<span class="attr">#[cfg(feature = <span class="string">"rustc-rayon"</span>)]
</span><span class="kw">mod </span>rustc;

<span class="kw">pub use </span><span class="kw">crate</span>::map::IndexMap;
<span class="kw">pub use </span><span class="kw">crate</span>::set::IndexSet;
<span class="kw">pub use </span>equivalent::Equivalent;

<span class="comment">// shared private items

</span><span class="doccomment">/// Hash value newtype. Not larger than usize, since anything larger
/// isn't used for selecting position anyway.
</span><span class="attr">#[derive(Clone, Copy, Debug, PartialEq)]
</span><span class="kw">struct </span>HashValue(usize);

<span class="kw">impl </span>HashValue {
    <span class="attr">#[inline(always)]
    </span><span class="kw">fn </span>get(<span class="self">self</span>) -&gt; u64 {
        <span class="self">self</span>.<span class="number">0 </span><span class="kw">as </span>u64
    }
}

<span class="attr">#[derive(Copy, Debug)]
</span><span class="kw">struct </span>Bucket&lt;K, V&gt; {
    hash: HashValue,
    key: K,
    value: V,
}

<span class="kw">impl</span>&lt;K, V&gt; Clone <span class="kw">for </span>Bucket&lt;K, V&gt;
<span class="kw">where
    </span>K: Clone,
    V: Clone,
{
    <span class="kw">fn </span>clone(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="self">Self </span>{
        Bucket {
            hash: <span class="self">self</span>.hash,
            key: <span class="self">self</span>.key.clone(),
            value: <span class="self">self</span>.value.clone(),
        }
    }

    <span class="kw">fn </span>clone_from(<span class="kw-2">&amp;mut </span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) {
        <span class="self">self</span>.hash = other.hash;
        <span class="self">self</span>.key.clone_from(<span class="kw-2">&amp;</span>other.key);
        <span class="self">self</span>.value.clone_from(<span class="kw-2">&amp;</span>other.value);
    }
}

<span class="kw">impl</span>&lt;K, V&gt; Bucket&lt;K, V&gt; {
    <span class="comment">// field accessors -- used for `f` instead of closures in `.map(f)`
    </span><span class="kw">fn </span>key_ref(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>K {
        <span class="kw-2">&amp;</span><span class="self">self</span>.key
    }
    <span class="kw">fn </span>value_ref(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>V {
        <span class="kw-2">&amp;</span><span class="self">self</span>.value
    }
    <span class="kw">fn </span>value_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;mut </span>V {
        <span class="kw-2">&amp;mut </span><span class="self">self</span>.value
    }
    <span class="kw">fn </span>key(<span class="self">self</span>) -&gt; K {
        <span class="self">self</span>.key
    }
    <span class="kw">fn </span>value(<span class="self">self</span>) -&gt; V {
        <span class="self">self</span>.value
    }
    <span class="kw">fn </span>key_value(<span class="self">self</span>) -&gt; (K, V) {
        (<span class="self">self</span>.key, <span class="self">self</span>.value)
    }
    <span class="kw">fn </span>refs(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; (<span class="kw-2">&amp;</span>K, <span class="kw-2">&amp;</span>V) {
        (<span class="kw-2">&amp;</span><span class="self">self</span>.key, <span class="kw-2">&amp;</span><span class="self">self</span>.value)
    }
    <span class="kw">fn </span>ref_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; (<span class="kw-2">&amp;</span>K, <span class="kw-2">&amp;mut </span>V) {
        (<span class="kw-2">&amp;</span><span class="self">self</span>.key, <span class="kw-2">&amp;mut </span><span class="self">self</span>.value)
    }
    <span class="kw">fn </span>muts(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; (<span class="kw-2">&amp;mut </span>K, <span class="kw-2">&amp;mut </span>V) {
        (<span class="kw-2">&amp;mut </span><span class="self">self</span>.key, <span class="kw-2">&amp;mut </span><span class="self">self</span>.value)
    }
}

<span class="kw">trait </span>Entries {
    <span class="kw">type </span>Entry;
    <span class="kw">fn </span>into_entries(<span class="self">self</span>) -&gt; Vec&lt;<span class="self">Self</span>::Entry&gt;;
    <span class="kw">fn </span>as_entries(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>[<span class="self">Self</span>::Entry];
    <span class="kw">fn </span>as_entries_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;mut </span>[<span class="self">Self</span>::Entry];
    <span class="kw">fn </span>with_entries&lt;F&gt;(<span class="kw-2">&amp;mut </span><span class="self">self</span>, f: F)
    <span class="kw">where
        </span>F: FnOnce(<span class="kw-2">&amp;mut </span>[<span class="self">Self</span>::Entry]);
}

<span class="doccomment">/// The error type for [`try_reserve`][IndexMap::try_reserve] methods.
</span><span class="attr">#[derive(Clone, PartialEq, Eq, Debug)]
</span><span class="kw">pub struct </span>TryReserveError {
    kind: TryReserveErrorKind,
}

<span class="attr">#[derive(Clone, PartialEq, Eq, Debug)]
</span><span class="kw">enum </span>TryReserveErrorKind {
    <span class="comment">// The standard library's kind is currently opaque to us, otherwise we could unify this.
    </span>Std(alloc::collections::TryReserveError),
    CapacityOverflow,
    AllocError { layout: alloc::alloc::Layout },
}

<span class="comment">// These are not `From` so we don't expose them in our public API.
</span><span class="kw">impl </span>TryReserveError {
    <span class="kw">fn </span>from_alloc(error: alloc::collections::TryReserveError) -&gt; <span class="self">Self </span>{
        <span class="self">Self </span>{
            kind: TryReserveErrorKind::Std(error),
        }
    }

    <span class="kw">fn </span>from_hashbrown(error: hashbrown::TryReserveError) -&gt; <span class="self">Self </span>{
        <span class="self">Self </span>{
            kind: <span class="kw">match </span>error {
                hashbrown::TryReserveError::CapacityOverflow =&gt; {
                    TryReserveErrorKind::CapacityOverflow
                }
                hashbrown::TryReserveError::AllocError { layout } =&gt; {
                    TryReserveErrorKind::AllocError { layout }
                }
            },
        }
    }
}

<span class="kw">impl </span>core::fmt::Display <span class="kw">for </span>TryReserveError {
    <span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, f: <span class="kw-2">&amp;mut </span>core::fmt::Formatter&lt;<span class="lifetime">'_</span>&gt;) -&gt; core::fmt::Result {
        <span class="kw">let </span>reason = <span class="kw">match </span><span class="kw-2">&amp;</span><span class="self">self</span>.kind {
            TryReserveErrorKind::Std(e) =&gt; <span class="kw">return </span>core::fmt::Display::fmt(e, f),
            TryReserveErrorKind::CapacityOverflow =&gt; {
                <span class="string">" because the computed capacity exceeded the collection's maximum"
            </span>}
            TryReserveErrorKind::AllocError { .. } =&gt; {
                <span class="string">" because the memory allocator returned an error"
            </span>}
        };
        f.write_str(<span class="string">"memory allocation failed"</span>)<span class="question-mark">?</span>;
        f.write_str(reason)
    }
}

<span class="attr">#[cfg(feature = <span class="string">"std"</span>)]
#[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"std"</span>)))]
</span><span class="kw">impl </span>std::error::Error <span class="kw">for </span>TryReserveError {}
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